Should fix the current failure that "master" does not exist.
I am a bit curious why master does not exist, maybe the CircleCI
git is set up to use some other default.
Move the branch rename to after the commit, to make sure that
the fact that the branch is empty (and `git branch` also)
cannot influence the result.

[ci-skip]

It seems the git in the CircleCI environment does not have the
`--initial-branch` option that my local git has, hopefully
`git branch -m` works fine.

The default of git is still "master", so we need to set
`--initial-branch=main` to ensure that we use the name `main`
that is used in the devdoc repository.

Closes gh-18568